Converts and outliers are of course are excluded, but for people with a long Jewish ancestry, there are clusterings of genetic markers that uniquely identify them as distinct from non-Jews. There are different groups of Jews too.

Judaism is well accepted as being both a race and a religion. Of course it has fuzzy borders with people who don't believe the religion but are genetically Jewish and vise versa, but so does every race and every religion.

It's not helpful for thought to demonize an idea by calling it "filth". How can you consider possibilities if you've decided in advance what's clean and what's too dirty to even say?